Pirfenidone (Deskar®), 5-methyl-1-phenyl-1H-pyridin-2-one, is an orally administered antifibrotic agent. Pirfenidone is effective in rodent disease models. Pirfenidone inhibits DNA synthesis in leiomyoma cells and myometrial cells (Lee et al, Journal of Clinical Endocrinology and Metabolism 1998, 83(1), 219-23). Pirfenidone is currently undergoing Phase III enrollment for idiopathic pulmonary fibrosis (IPF).

While the chemical structure of pirfenidone is relatively simple, the metabolism is only partially understood. For example, the methyl group is thought to be susceptible to oxidation which would lead to a corresponding hydroxymethyl metabolite, “M1.” M1 is thought to be further oxidized to a carboxylic acid metabolite, “M2” (Wang et al, Biomedical Chromatography 2006, 20, 1375-1379). A third detected metabolite is believed to be a phase II product possibly originating from M1 or M2. Pirfenidone has a very short half-life in humans and will likely be dosed at more than once per day.